You also can not determine, if you are back to the very original version you loaded in step1.Undo list is limited, after reaching capacity old entries are discarded.

1) load file2) edit / add more undo entries than capacity3) undo all existing entries since some undo got discarded, you are still not back to 1

That said, there may be other reason for exposing the count.You can add a feature request on our bug tracker. But it will not be any time soon. Patches welcome, but a test case should be included. (simulating with/without grouped undo / mixing undo and redo / ...)